Alembic Guitars Club
Alembic products => Alembic Basses & Guitars => Topic started by: Picure on September 18, 2018, 03:42:35 AM
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Hello, I am looking to add ferrite beads to each of the pickups on my 80’s Series 1 because I experienced RF interference on one gig and high frequency directional noise from lights on another gig. On both instances, the hum canceller was unable to eliminate the problem.
What I would like to ask is if a ferrite bead would help this problem? Because right now I am unable to send her back to the mothership for “The Upgrade”. Also, would it be a good idea to get shielding paint done in the cavity?
Thanks!
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They don't need your whole bass to do the upgrade, just the preamp card.
I would recommend that you send it to Alembic!
You will be happy that you did.
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Oh of course I would send my bass back to Alembic for upgrades. However I have an upcoming tour that I would like to use this bass for. Also, I want to bring my bass to Alembic in person. Im planning a trip to Mexico with my wife next year and I am thinking of swingig by Santa Rosa on the way.
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Not sure if you understood what I said...
If you want Alembic to do the RF upgrade, all they need is the preamp card (not the whole bass)
Just pull the card and send it to them.
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Yea, I completely understood you. However, I need this bass for work and am unable to send it back for the time being. Also, I want to have Alembic do more than just the RF upgrade for me. I am looking to do an complete overhaul. But for the time being, I'm wondering if there is something I could do to make the RF/HF noise a bit more tolerable when present.
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Jack,
This is indeed part of the Alembic Series I and II experience. Because of our large full-range single-coil pickups, and the fact that the hum cancelling coil is not stacked directly under the pickup coil, rejection of audio frequency interference can be an issue. Worse if you raise the noise floor by heavily compressing the bass signal...
But this pickup arrangement together with the great preamp electronics are also the reason these basses sound so amazing. So for me it's always been worthwhile to find a workaround to the noise issue. That used to mean just turning the instrument to find the quietest position, even if that sometimes meant pointing the neck directly at the audience. Ha!
I have no experience with ferrite beads so can't say what impact they might have in this situation. I could be wrong but I don't think that technology would apply here.
Your bass should already have its cavity coated with shielding paint, it came from the factory that way. It should look silver in there and you should find electrical continuity between the 1/4" jack and any of the backplate screws.
And unless Ron's magic upgrade method has changed, it's my understanding that they DO need the entire bass for that. The build of the instrument, including where the brass plates are, effects the noise rejection. Ron hand-tunes the card to match each individual instrument. I could be wrong about that too, maybe there is now a simpler option that can be done to the card alone?
So apart from: 1. finding the quiet direction, 2. judicious use of your standby switch, or 3. perhaps an in-line volume pedal, there isn't much to be done beyond getting the bass to Alembic HQ for the upgrade.
We're glad to hear you're enjoying the bass and hope you can find a way to make it your main axe! It would also be great is you can make it by the factory on your trip to this side of the planet. That's a unique experience and bound to make you more of an Alembic nut than you already are. :)
Jimmy J
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I don't think you're going to have any useful result from a ferrite bead with the single coil pickups in a Series I or II bass.
Jimmy is correct - to do the RF upgrade, the whole bass is needed here. I wish it wasn't needed, but even very small variations in the placement of the brass parts makes a huge difference in the engineering for the upgrade.
You can alternatively replace the three pickups with a hyper-matched set yourself. This is the first step in most upgrades, and will usually take care of at least 50% reduction in the RF issue, which may put it in the realm of usable for you.
The RF issue is highly location specific - it can be dead quiet in one place and then another location is noisy noisy noisy. It all depends on the number and strength of the high frequency noise sources in the region.
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oops
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The humcanceller will only address low-frequency hum (or the harmonics of it).
And yes, your cavities were shielded when new with pure elemental silver paint. Unless it was later covered by careless refinishing, or scratched away or breached in some other fashion, it will still work just fine. You can add a picture of the interior of the cavity for us to inspect and see if it looks good, and as Jimmy describes, you can check it as well.
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Passed some hard times with RFI when I got my Rogue. Radio transmission laws in Brazil are little loose and there are places where radio broadcast can really get into Alembic's PU (don't know what causes it). Although I still find a few venues where I need to find the quiet spot to perform (or having to be still, change entire rig's place or turn volume down during pauses), I've found that just one single PU cable was looping through the ferrite bead and correcting it did the job. When I passed both cables through it, the issue got fairly controled (now it just happens in one specific place in this really big city of Sao Paulo, the highest ground where all radios and TVs gather to broadcast). Worth giving it a try, although Series may be more sensitive than a Rogue's circuit.
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Thanks a million to all of you guy’s replies and support! Last night, before recieving your replies, I already installed a ferrite bead to each of the pickup wires. I guess that even if they dont work it shouldnt be of much harm leaving them inside. I think my best option for now is to get myself a set of hyper matched pickups. I would like to ask, does they Hyper Matched pickups include the hum canceller too? Because I’m a bit reluctant on removing the original hum canceller because of “The Rubber Mallet” haha.
Thanks!
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The humcanceller will only address low-frequency hum (or the harmonics of it).
And yes, your cavities were shielded when new with pure elemental silver paint. Unless it was later covered by careless refinishing, or scratched away or breached in some other fashion, it will still work just fine. You can add a picture of the interior of the cavity for us to inspect and see if it looks good, and as Jimmy describes, you can check it as well.
Here are the pics. Thanks!
(https://dl.dropboxusercontent.com/s/41o2wv387nvpptd/Photo%202018-9-20%2C%2012%2021%2041%20AM.jpg?dl=0)
(https://dl.dropboxusercontent.com/s/kmxk2rxwdwqwpln/Photo%202018-9-20%2C%2012%2021%2056%20AM.jpg?dl=0)
(https://dl.dropboxusercontent.com/s/6vavjyp9ocoizss/Photo%202018-9-20%2C%2012%2022%2004%20AM.jpg?dl=0)
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... I've found that .. looping through the ferrite bead .. did the job ...
My recollection is that non-Series instruments do benefit from a ferrite bead, but not Series instruments.
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The shielding looks original and good, with no shiny refinish coating so that's great. The beads will neither help nor harm the high frequency interference, so it's OK to leave them as long as they don't bang around (read: add some foam to keep them in place).
The hyper matched set does include the HX pickup. You can try just the single coils first, and that may be good enough. You can always do the HX pickup at a later time, but you need to get the set of three at the same time so they have the best possible matching.
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I second Jimmy’s advice (as if anyone would disagree with Jimmy on any bass issue). Finding he workaround is preferable to seeking he perfect technical solution, which is usually elusive. A volume pedal, rolling off the HF if there is HF interference,” damping more than we’d prefer to limit the bass boom, turning to the “quiet” orientation etc. - that’s what we do. Very frustrating- but bass players are famous for our laid-back vibe. No matter what technical solutions you find, there will be a technical problem to defeat it. So - we are left to improvise. And I think we do pretty well!
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Instead of a volume pedal to cut extraneous noise in between tunes, you might also consider a noisegate pedal which will do the same thing automatically.
Bill, tgo
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One other thing to try is rolling off the high end some. Many years ago my band use to play a venue in Chicago. I was playing my Jazz Bass which I has built a preamp into along with all of the shielding I could manage. The only way I could get rid of WXRT was to reduce the treble on the bass and amp. Not the ideal sound but it worked. Now that I look back on it would have been a great way to get music during the break.